Alright Dave, can I hazard a guess you're around 6' or more?
I had mine done by Saxon Seats down in Dorchester, as did another from this forum.



I had the seat height raised, firmer foam, gel and the seat was widened and the cut out moved back. I can do a ride non stop til the tank need fuel no worries.
Speak to http://www.saxonseats.co.uk/ I think the guy that dealt with me was called Adam, very helpful.